Process for making butyl ethers of glycols

Abstract

Processes are described for the preparation of glycol butyl ethers involving reaction of butadiene with saturated aliphatic glycols, separating the thus formed n- and sec-butenyl glycol ethers and hydrogenating the n-butenyl glycol ethers. Additional features are the use in the first step of heterogeneous catalyst modified by alkylpyridinium quaternary ammonium, quaternary arsonium quaternary phosphonium counterions and/or the conversion of sec-butenyl glycol ethers to butadiene and saturated aliphatic glycols.

What is claimed is:  
     
       1. A process for the production of n-butyl glycol ether which comprises: 
       i. forming a mixture of n-butenyl glycol ether and secondary butenyl glycol ether by reacting butadiene with a saturated aliphatic glycol in the presence of a heterogeneous catalyst which is modified by the addition of at least one counterion selected from the group consisting of: an alkyl pyridinium, quaternary ammonium, quaternary arsonium and quaternary phosphonium;  
       ii. separating the n-butenyl glycol ether and secondary butenyl glycol ether formed in step i), and  
       iii. hydrogenating the n-butenyl glycol ether separated in step ii) in the presence of a catalyst to the corresponding n-butyl glycol ether.  
     
     
       2. A process as claimed in  claim 1 , wherein the secondary butenyl glycol ether separated from the mixture of crotyl glycol ether and secondary butenyl glycol ether is recycled back to step i). 
     
     
       3. A process for the production of a saturated butyl glycol ether which comprises: 
       a. reacting butadiene with a saturated glycol ether in the presence of a catalyst in a first reaction zone to produce a mixture of n-butenyl glycol ether and sec-butenyl glycol ether;  
       b. separating the n-butenyl glycol ether and secondary butenyl glycol ether formed in step a),  
       c. hydrogenating the n-butenyl glycol ether separated in step b), and  
       d. contacting the secondary butenyl glycol ether separated in step b) with a catalyst in a second reaction zone to convert the secondary butenyl glycol ether into the starting butadiene and saturated aliphatic glycol.  
     
     
       4. A process as claimed in  claim 3 , wherein the n-butenyl glycol ether separated in step b) is hydrogenated in step c) in the presence of a heterogeneous catalyst. 
     
     
       5. A process as claimed in  claim 3 , wherein step a) is carried out in the presence of a catalyst which is modified by the addition of a counterion selected from the group consisting of: an alkyl pyridinium quaternary ammonium, quaternary arsonium and quaternary phosphonium. 
     
     
       6. A process as claimed in any preceding claim wherein the n-butyl glycol ether produced is a mono-n-butyl ether of ethylene glycol. 
     
     
       7. A process as claimed in  claim 1  wherein the butadiene employed in step i) is in the form of a feed stream consisting essentially of butadiene, or is in the form of a hydrocarbon stream comprising butadiene. 
     
     
       8. A process as claimed in  claim 1 , wherein the catalyst employed to catalyse the reaction between butadiene and the saturated aliphatic glycol is a heterogeneous catalyst selected from the group consisting of: liquid acidic polymers, HY zeolites, strong acid macrorecticular and gel type ion exchange resins and supported heteropolyacids of tungsten or molybdenum. 
     
     
       9. A process as claimed in  claim 3 , wherein the catalyst in the second reaction zone is a Brønstead or Lewis acid. 
     
     
       10. A process as claimed in  claim 9 , wherein the catalyst in the second reaction zone, is the same as the catalyst employed in the first reaction zone.